Lawn mowers have been in use for decades and earlier mowers, the reel-type, involved a multi-bladed reel rotating about a horizontal axis. The blades, curved along their length, moved across a stationary sharpened bar to cut blades of grass. Later, the rotary mower was introduced with its vertical drive shaft, horizontal high-speed cutting blade and jet-like exhaust port from which streamed the grass clippings.
But when using either type of mower, the cut top portions of blades of grass were often simply left on the lawn to decompose. In the alternative, such portions were raked from the lawn and discarded or collected in a catch basket (using a reel mower) or a collection bag using a rotary mower. Either choice could be detrimental.
If the "cover" of cut grass was too thick, the underlying grass may well be killed. And in any event, "yellowing" of such underlying grass was very common as the cover of cut grass prevented moisture from escaping and prevented sunlight from reaching the grass. On the other hand, if the cut grass portions were removed, the lawn was deprived of nourishment that otherwise would have been obtained from such portions.
A motivation for development of the mulching mower was the recognition of the fact that grass nutrients were being discarded. The mulching mower is a type of rotary mower but differs therefrom chiefly in the fact that the mulching mower has two cutting blades, rather than one, and no exhaust port. The idea is that the grass portions initially cut by the rotating blades are "recirculated" within the area swept by the blades and cut again, perhaps several times, into more finely-divided pieces of grass.
But the mulching mower is not entirely free of problems. As a general observation, such mowers work well for their intended purpose only if a lawn is cut frequently, perhaps much more often than once per week when ample rain falls. But many mower users mow their lawn only once per week; time often does not permit more frequent mowing.
If a mulching mower is used only when grass is long, such mower tends to "bunch" the cut portions of grass into fist-sized lumps which are deposited on the grass. Such lumps can have the deleterious, grass-killing effect described above.
And the matter of yard care has another aspect which is not addressed by any known type of conventional mower, mulching or otherwise. Home owners often need to dispose of branches trimmed from trees. Many refuse collection companies will not remove such branches and many municipalities prohibit lawn waste from being deposited into landfills.
To meet these emerging needs, a machine known as a chipper-shredder has been introduced and examples of such machines are depicted in U.S. Pat. Nos. 5,156,345 (Baker); 5,102,056 (Ober); 4,824,034 (Baker) and others. Such machines are configured to mulch leaves and chip branches and twigs. As to the latter, small wood chips are advantageously used as a mulching covering around tree, bushes and the like. But such machines have neither a grass mowing nor a grass mulching capability. Thus, for complete yard care, the homeowner is required to purchase (and store and maintain) at least two machines, namely, a mower and a chipper-shredder.
An improved yard-care machine which addresses and overcomes some of the disadvantages of prior art machines would be an important advance in the art.